Expression of cholecystokinin by neurons in mouse spinal dorsal horn
2019
Excitatory interneurons account for the majority of dorsal horn neurons, and are required for
perception of normal and pathological pain. We have identified largely non-overlapping populations
in laminae I-III, based on expression of substance P, gastrin-releasing peptide, neurokinin B and
neurotensin. Cholecystokinin (CCK) is expressed by many dorsal horn neurons, particularly in the
deeper laminae. Here we have used immunocytochemistry and in situ hybridisation to characterise
the CCK cells. We show that they account for ~7% of excitatory neurons in laminae I-II, but
between a third and a quarter of those in lamina III. They are largely separate from the neurokinin
B, neurotensin and gastrin-releasing peptide populations, but show limited overlap with the
substance P cells. Laminae II-III neurons with protein kinase Cγ (PKCγ) have been implicated in
mechanical allodynia following nerve injury, and we found that around 50% of CCK cells were
PKCγ-immunoreactive. Neurotensin is also expressed by PKCγ cells, and among neurons with
moderate to high levels of PKCγ, ~85% expressed CCK or neurotensin. A recent transcriptomic
study (Haring et al, Nat. Neurosci., 2018) identified mRNA for thyrotropin-releasing hormone
(TRH) in a specific subpopulation of CCK neurons, and we show that these account for half of the
CCK/PKCγ cells. These findings indicate that CCK cells are distinct from other excitatory
interneuron populations that we have defined. They also show that PKCγ cells can be assigned to
different classes based on neuropeptide expression, and it will be important to determine the
differential contribution of these classes to neuropathic allodynia.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
53
References
19
Citations
NaN
KQI